1. Field of the Invention
The present invention relates to a conical nib and a writing instrument incorporating the same. More particularly, the invention relates to a conical nib having high wear resistance and a writing instrument incorporating the same.
2. Description of the Related Art
A writing instrument including this kind of conical nib is disclosed in Japanese Unexamined Patent Application, First Publication No. H9-156279. A nib of the disclosed writing instrument includes a nib base body and a converging member. The nib base body includes a cylindrical base portion and five to eight combtooth pieces. The combtooth pieces protrude from an end of the base portion in a continuous manner. Each of the combtooth pieces has a circular-arc cross section. The combtooth pieces have slit-like grooves formed between adjacent combtooth pieces at a constant interval along a circumference of an axial center of the base portion. A hemisphere-divided portion is defined at a tip of each combtooth piece. The converging member is a metal pipe configured to fit onto an outer periphery of the nib base body. When the converging member is fit onto the nib base body, the combtooth pieces are made to gradually converge toward the tips thereof to forma conical shape. A hemispherical writing tip is defined at the tips of the combtooth pieces and ink feed paths are defined between adjacent combtooth pieces.
An ink feed core which has a capillary action reaching a tip thereof is inserted in a hollow space in the nib (i.e., the pen nib base body). The ink feed core is secured integrally to a tip of the pen shaft. The ink feed core is connected to an ink reservoir inside the pen shaft. The thus-configured nib can be used to write in many directions on a paper sheet. The nib can be used to write at any positions and at any angles, even when rotated about the pen shaft. Characters of varying width can be written in accordance with varying writing pressure. Recently, in order to meet demands on mass production and improvement in formability, the combtooth pieces are often formed of an injection-molded plastic material.
Writing instruments incorporating such plastic conical nibs, however, have poor wear resistance at the nibs and the nibs are easy to wear as compared with metal nibs or ceramic nibs.
The invention is made to solve these related art problems. An object of the invention is therefore to provide a plastic conical nib having high wear resistance and a writing instrument incorporating the same.